Neck brace

ABSTRACT

A method of using a neck brace to move a neck of a person or stabilize the neck includes connecting a vest of the neck brace to a torso of a person. A support member of the neck brace is connected to the vest. A chin support of the neck brace is connected to a chin of the person. Force is applied between the support member and the chin support to move the chin support relative to the support member. A cam member of the neck brace guides movement of the chin support relative to the support member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a continuation of U.S. patent application Ser. No. 10/329,866, filed Dec. 26, 2002, now U.S. Pat. No. 6,770,047 which is a continuation of U.S. patent application Ser. No. 09/728,106, filed Dec. 1, 2000 (now U.S. Pat. No. 6,503,213 B2). The entire content of each of these applications is expressly incorporated herein by reference thereto.

FIELD OF THE INVENTION

The present invention relates to a new and improved method of using a neck brace.

BACKGROUND OF THE INVENTION

A known neck brace for stabilizing a neck of a person is disclosed in U.S. Pat. No. 4,793,334. The neck brace disclosed in this patent includes a framework and straps for securing the framework to the body. A chin support member is positioned relative to the framework to present movement of the neck. The chin support member is supported on a strut. The strut is releasably and pivotally mounted to the framework. A brace member extending from the strut provides pivotable movement of the strut.

SUMMARY OF THE INVENTION

The present invention provides a novel method for using a neck brace to move a neck of a person or stabilize the neck. The method includes connecting a vest of the neck brace to a torso of the person. A support member of the neck brace is connected to the vest. A chin support of the neck brace is connected to a chin of the person. Force is applied between the support member and the chin support to move the chin support relative to the support member. A cam member guides movement of the chin support relative to the support member.

The chin support may be moved relative to the support member after the support member is connected to the torso of the person and the chin support is connected to the chin. Accordingly, upon applying force between the support member and the chin support, the chin is moved relative to the torso to move the neck of the person. The neck brace allows stretching and distraction of the neck. The neck brace can be used to stretch the neck of burn patients as well as for possible distraction of the neck for people with disc problems.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the invention will become more apparent upon consideration of the following description taken in connection with the accompanying drawings, wherein:

FIG. 1 is an illustration of a neck brace constructed in accordance with the present invention;

FIG. 1A is an illustration of the neck brace of FIG. 1 connected to a person;

FIG. 2 is a schematic side view of a portion of the neck brace of FIG. 1;

FIG. 3 is an enlarged sectional view of the neck brace taken generally along the line 3-3 in FIG. 2;

FIG. 4 is a schematic side view of the neck brace of FIG. 1 depicting the manner in which the neck brace is operated to move the neck in flexion;

FIG. 5 is a schematic side view of the neck brace, generally similar to FIG. 4, depicting the manner in which the neck brace is operated to move the neck in extension; and

FIG. 6 is an illustration of a vest of the neck brace of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Neck Brace-General Description

A neck brace 10 (FIGS. 1 and 1A) can be used to move or stabilize a neck 22 of a person. The neck brace 10 includes a T-shaped support member 12 which is connected with a torso 14 of a person. A chin support 16 is connected with a chin 18 of the person. An actuator mechanism 20 moves the chin support 16 relative to the support member 12. The chin support 16 is moved relative to the support member 12 after the chin support is connected to the chin 18 and the support member is connected to the torso 14 to move the neck 22 of the person. The support member 12 and the chin support 16 may have any desired construction as long as they are effective to engage the torso 14 and the chin 18.

A cloth vest 30 (FIG. 1A), which will be described in detail hereinafter, connects the support member 12 with the torso 14. The chin support 16 (FIG. 1) includes a chin portion 32 formed to engage the chin 18. A back portion 34 of the chin support 16 for engaging the back of the neck 22 is connected to the portion 32 by an elastic band 36. The elastic band 36 extends through the back portion 34 and has opposite ends connected to the chin portion 32. Accordingly, the back portion 34 can move relative to the chin portion 32.

It is contemplated that the back portion 34 could be connected to the chin portion 32 in any manner that will permit adjustment of the back portion 34 relative to the chin portion and connection of the chin support 16 to the chin 18. Furthermore, it is also contemplated that the back portion 34 could have any shape which conforms to the back of a person's neck. The chin portion 32 could have any shape that conforms to the chin 18.

A pair of interconnecting members or arms 38 (FIGS. 1 and 1A) connect the chin support 16 with the support member 12. The arms 38 extend from the chin support 16 to the actuator mechanism 20. Each of the arms 38 has an upper end 40 with a slot 44 (FIGS. 1 and 2). Threaded members 46 (FIG. 2) extend from the portion 32 of the chin support 16 through the slots 44. Clamping members 48 threadably engage the threaded members 46 to clamp the ends 40 of the arms 38 to the portion 32. The portion 32 can be positioned relative to the arms 38 when the clamping members 46 are loosened from the threaded members 46. The portion 32 can be pivoted about the threaded members 46 and the threaded members can be moved between the ends of the slots 44 to position the chin support 16 relative to the arms 38.

The actuator mechanism 20 (FIGS. 1 and 2) is connected to a pivot support 50 connected to a support plate 52 of the support member 12. The actuator mechanism 20 is connected to the pivot support by a pivot connection 54. The actuator mechanism 20 transmits force between the support member 12 and the chin support 16 to simultaneously pivot the actuator mechanism about a pivot axis of the pivot connection 54 and move the interconnecting members 38 relative to the actuator mechanism.

The actuator mechanism 20 transmits force from an input member which, in the illustrated embodiment of the neck brace 10, is a manually rotatable knob 56. Force is transmitted from the knob 56 through the actuator mechanism 20 to the chin support 16. Force is transmitted from the actuator mechanism 20 to pivot the actuator mechanism about the pivot connection 54. In addition, force is transmitted from the knob 56 to move the interconnecting members 38 and the chin support 16 relative to the actuator mechanism 20 as the actuator mechanism pivots about the pivot connection 54.

A frame 60 (FIGS. 1 and 2) of the actuator mechanism 20 has a lower housing 68 and an upper housing 70 joined by a front plate 72 and a back plate 74. The back plate 74 is connected to the pivot support 50 by the pivot connection 54. A drive mechanism 62 for the neck brace 10 is disposed substantially within the frame 60. The drive mechanism 62 includes the manually actuatable knob 56 which is fixed to a shaft 80. The shaft 80 (FIG. 3) extends into the frame 60 and a gear 82 is fixed to the shaft. The gear 82 engages external gear teeth 84 on a gear 86. Rotation of the gear 80 about its axis causes rotation of the gear 86 about its axis.

The gear 86 (FIG. 3) is fixed to an externally threaded member 92. The gear 86 is journalled for rotation in the lower housing 68. The opposite end of the screw 92 is journalled for rotation in a bushing 96 mounted in the upper housing 70 of the frame 60. A base link 100 has an internally threaded opening 102 through which the screw 92 extends in threaded engagement. As the screw 92 rotates, the base link 100 moves axially along the screw within the frame 60.

The interconnecting arms 38 (FIGS. 2 and 3) are fixedly connected to the base link 100 by screws 110. The screws 110 also fixedly connect links 120 to the base link 100 and the arms 38. The links 120 extend from the base link 100 toward the support member 12.

A pin 124 (FIG. 2) is connected to ends 126 of the links 120 by screws 128. The pin 124 extends between the ends 126 of links 120 and through a slot 130 in a cam member 132 connected with the support plate 52. The slot 130 in the cam member 132 guides movement of the pin 124 relative to the support member 12. Accordingly, the slot 130 guides movement of the base link 100, the interconnecting members 38, and the chin support 16 relative to the support member 12.

The slot 130 (FIG. 2) has a first or upper end portion 136 and a second or lower end portion 138. The upper and lower end portions 136 and 138 of the slot 130 extend in directions generally parallel to each other and the support plate 52. An intermediate portion 140 of the slot 130 extends between the end portions 136 and 138. The slot 130 guides movement of the links 120, base link 100, interconnecting members 38, and chin support 16 along paths having first and second end portions extending in directions generally parallel to each other and intermediate portions extending between the first and second end portions.

The actuator mechanism 20 is operable to move the chin support 16 and the chin 18 from an initial position, such as the one shown in FIG. 4, to actuated positions, such as the one shown in FIG. 5. Operation of the actuator mechanism 20 moves the chin support 16 along the path having first and second end portions extending in directions generally parallel to each other and an intermediate portion extending between the first and second end portions. As this occurs, the frame 60 pivots about the pivot connection 54 and the interconnecting members 38 move relative to the frame.

Moving Neck in Extension

When the input knob 56 is manually rotated in the direction of arrow 150 in FIG. 1, the actuator mechanism 20 is operated. Operation of the actuator mechanism 20 transmits force from the knob 56 to the base link 100. The base link 100 and arms 38 move in an upward direction as view in FIG. 4 from the orientation shown in FIG. 4 toward the orientation shown in FIG. 5 to move the neck 22 in extension.

Operation of the actuator mechanism 20 moves the base link 100 and the interconnecting members 38 away from the lower housing 68. As the base link 100 moves away from the lower housing 68, the links 120 move with the base link. Accordingly, the pin 124 moves along the slot 130 from the lower end portion 138 to the intermediate portion 140 and to the upper end portion 136. As the pin 124 moves along the slot 130, the frame 60 pivots in a counterclockwise direction (as viewed in FIGS. 4 and 5) about the pivot connection 54. Simultaneously therewith, the interconnecting members 38 move relative to the frame 60. Pivotal movement of the frame 60 causes the chin support 16, the interconnecting members 38, and the base link 100 to move about the pivot axis of the pivot connection 54. As the interconnecting members 38 move relative to the frame 60 and the frame pivots about the pivot connection 54 toward the orientation shown in FIG. 5, the neck 22 is moved in extension.

During movement of the interconnecting members 38 relative to the frame 60 and movement of the neck 22 in extension, the actuator mechanism 20 transmits force to the chin support 16. The interconnecting members 38 move relative to the frame 60 and the frame pivots about the pivot connection 54. In the illustrated embodiment of the invention, the interconnecting members 38 and the frame 60 are moved by the actuator mechanism 20 through a range of movement from the positions shown in FIG. 4 to a condition of maximum extension as shown in FIG. 5. When the links 120 are in the positions shown in FIG. 5, notches 152 in the links 120 extend around screws 154 of the pivot connection 54. It should be understood that the foregoing specific range of movement of the neck brace 10 has been set forth herein for purposes of clarity of description and that it is contemplated that specific embodiments of the neck brace will have interconnecting members 38 and a frame 60 which move through different distances relative to each other and are movable to different angular orientations relative to the support member 12.

It is contemplated that the specific procedure which is followed to move the neck 22 in extension will vary depending upon the conditions of the neck and the desires of a surgeon or therapist supervising the use of the neck brace 10. However, it is believed that it may be preferred to use a static progressive stretch procedure during movement of the neck 22. This procedure is implemented by operating the actuator mechanism 20 to move the neck 22 in extension to a limit of tolerance of the neck without severe pain. This position of the neck 22 is held for a period of time, for example, five minutes, to allow the tissue of the neck to relax. As the tissue relaxes, stress decreases. After the period of time has elapsed, the input member is manually rotated to again stretch the tissue of the neck 22 to the limit of tolerance. This condition is again held for a period of time, for example, five minutes, to allow the tissue in the neck 22 to again relax. The process is repeated for the duration of a therapy session which, may be approximately 30 minutes long.

The input knob 56 may be manually rotated by either the patient, that is, the person having the neck 22 on which the neck brace 10 is mounted, or by a supervisory personnel, such as a therapist. However, it is believed that it will be desired to have the patient actuate the neck brace 10 to affect movement of the neck 22. The patient can feel when the tissue has tightened and the neck 22 has been moved to the limit of its tolerance, without severe pain. The patient can also feel when the tissue has relaxed and further actuation of the neck brace 10 to further move the neck 22 in extension can be undertaken.

Moving Neck in Flexion

When the neck 22 is to be moved in flexion, the input knob 56 is manually rotated, in the direction of arrow 158 in FIG. 1, to operate the actuator mechanism 20. Operation of the actuator mechanism 20 transmits force from the input knob 56 to the base link 100. As the input knob 56 is manually rotated, the actuator mechanism 20 moves the base link 100 toward the lower housing 68 and away from the upper housing 70. Thus, the links 120 are moved from the position shown in FIG. 5 toward the position shown in FIG. 4 as the input knob 56 is manually rotated.

As the base link 100 is moved toward the lower housing 68, the links 120 move downward, as viewed in FIG. 5. As the links 120 move downward, the pin 124 moves along the slot 130 from the upper end portion 136 through the interconnecting portion 140 to the lower end portion 138. Thus, the interconnecting members 38 move relative to the frame 60 and the frame pivots in a clockwise direction (as viewed in FIG. 5) about the pivot connection 54. As the interconnecting members 38 move and the frame 60 pivots, the neck 22 is moved in flexion from the initial condition shown in FIG. 5 toward the condition shown in FIG. 4.

As the interconnecting members 38 move relative to the frame 60 and the frame pivots about the pivot connection 54, the chin support 16 and the chin 18 are moved from the position shown in FIG. 5 toward the position shown in FIG. 4. Thus, force is transmitted from the actuator mechanism 20 to the interconnecting members 38 to move the chin support 16 along a path having first and second end portions extending in directions generally parallel to each other and an intermediate portion extending between the first and second end portions.

It is believed that a static progressive stretch procedure may be preferred for moving the neck 22 in flexion. Thus, the input knob 56 is manually rotated to operate the actuator mechanism 20 and affect movement of the chin support 16 to move the neck 22 in flexion until the patient feels tissue tightness, but not severe pain. The neck brace 10 is maintained in that position for a period of time, which may be five minutes. When the tissue relaxes, the input knob 56 is again rotated to stretch the tissue. The steps of operating the neck brace 10 to stretch the tissue, interrupting operation of the neck brace to allow the tissue to relax and then again operating the neck brace to again stretch the tissue is repeated for the duration of a therapy session.

As was previously mentioned, the knob 56 may be manually rotated by a therapist or surgeon. However, it is believed that it will be preferred to have the patient manually rotate the knob. Thus, the person having the neck 22 will rotate the knob 56 until he or she feels the tissue tighten and will further rotate the knob to further move the neck when he or she feels the tissue relax.

In the example of moving the neck 22 in flexion, illustrated in FIGS. 4 and 5, the neck is moved from an initial condition illustrated in FIG. 5. However, it is believed, that under certain circumstances, the neck may initially be in a condition between the conditions shown in FIGS. 4 and 5 and moved in flexion to the condition in FIG. 4. When this is to be done, the neck brace 10 is operated to move the neck 22 in flexion toward the condition illustrated in FIG. 4.

Stabilizing Neck

The neck brace 10 can be used to stabilize the neck 22 in a desired position. When the neck brace 10 is to be used to stabilize the neck 22, the vest 30 is connected with the torso 14. The support member 12 is placed over the chest and connected with the vest 30. The actuator mechanism 20 is operated by turning the knob 56 in the direction of arrow 150 or arrow 158 to move the interconnecting members 38 relative to the support member 12.

Operation of the actuator mechanism 20 transmits force from the input knob 56 to the base link 100. As the input knob 56 is rotated, the base link 100, the links 120, and the interconnecting members 38 move relative to the frame 60. The pin 124 moves along the slot 130. Accordingly, the interconnecting members 38 move along paths having first and second end portions extending in directions generally parallel to each other and intermediate portions extending between the first and second end portions. The interconnecting members 38 move relative to the frame 60 and the frame pivots about the pivot connection 54.

When the interconnecting members 38 have been moved to a desired position, the chin support 16 is connected with the chin 18. The chin support 16 is positioned relative to the interconnecting members 38. The clamping members 48 are threaded onto the threaded members 46 to clamp the interconnecting members 38 to the chin support 16. Once the neck brace 10 is connected to the person, operation of the actuator mechanism 20 is prevented so that the neck 22 is stabilized.

Actuator Mechanism

The actuator mechanism 20 (FIGS. 2 and 3) is supported on the pivot support 50 of the support member 12. The actuator mechanism 20 includes the externally threaded member 92 which is rotatably supported within the frame 60. A central axis of the screw 92 extends through the center of the base link 100.

The manually rotatable knob 56 is fixedly connected to the shaft 80. The shaft 80 (FIG. 3) has the gear 82 in meshing engagement with the gear 84 connected with the screw 92. The base link 100 has internal thread convolutions which engage with external thread convolutions on the screw 92. In the illustrated embodiment of the invention, the base link 100 is movable relative to the frame 60 and the screw 92. However, the frame 60 and the screw 92 could be movable relative to the base link 100. If this was done, the base link 100 would be connected with the support member 12 and the frame 60 would be connected with the interconnecting members 38.

Upon rotation of the input member or knob 56, the base link 100 moves relative to the screw 92 and the frame 60. As this occurs, the links 120 move with the base link 100 relative to the frame 60. Also, the interconnecting members 38 and the chin support 16 move relative to the frame 60 and the frame pivots about the pivot connection 54. Of course, movement of the interconnecting members 38 and the frame 60 moves the neck 22 with which the neck brace 10 is connected. Movement of the base link 100 toward the upper housing 70 moves the neck in extension. Movement of the base link 100 away from the upper housing 70 moves the neck 22 in flexion.

The base link 100 and the frame 60 can be moved from an initial condition between the conditions shown in FIGS. 4 and 5 to one of the actuated conditions shown in FIGS. 4 and 5. The base link 100 and the interconnecting members 38 move along paths having first and second end portions extending in directions generally parallel to each other and interconnecting portions extending between the first and second end portions. The base link 100 and the interconnecting members 38 are guided along the paths due to engagement of the pin 124 in the slot 130 of the cam member 132.

In the illustrated embodiment of the invention, the screw 92 has a thread so that the knob 56 is manually rotated in a clockwise direction, as indicated by arrow 150 in FIG. 1, to move the base link 100 toward the upper housing 70. When the knob 56 is manually rotated in a counterclockwise direction, the base link 100 moves away from the upper housing 70. It should be understood that an input member other than the knob 56 could be used to operate the actuator mechanism 20 if desired.

Vest

The support member 12 (FIGS. 1A and 6) is connected with the torso 14 of the person using the, vest 30. The vest 30 (FIG. 6) has a front portion 170 and a back portion 172. The front portion 170 has side portions 174 and 176. A catch member 177 is fixedly connected to the side portion 174 and is releasably connected to the side portion 176 to hold the side portions together when the vest 30 is worn. Shoulder portions 178 interconnect the front portion 170 and the back portion 172.

The shoulder portions 178 extend over the shoulders of the person when the vest 30 is connected to the torso 14. The front portion 170 covers the chest of the person. The back portion 172 covers the back of the person when the person is wearing the vest 30.

Shoulder straps 180 (FIGS. 1A and 6) are connected with the back portion 172 and extend over the shoulder portions 178 to connect the vest 30 to the person. The straps 180 also connect the support member 12 to the vest 30. The straps 180 extend through retainers 184 connected to the support member 12 to secure the support member to the vest 30.

A suitable strap 190 (FIGS. 1A and 6) extends around a mid-section of the person and through loops (not shown) on the back portion 172 of the vest 30. The strap 190 has opposite end portions 192 and 194. The end portions 192 and 194 of the strap 190 extend through retainers 198 connected with the support member 12 to further connect the support member to the vest 30 and the vest to the person.

Conclusion

The present invention provides a new and improved method for using a neck brace 10. The neck brace 10 can be used to stabilize the neck 22 or to move the neck in extension or flexion. The support member 12 is connected with a torso 14 of the person and a chin support 16 is connected with a chin 18 of the person. An actuator mechanism 20 is operated to move the chin support 16 relative to the support member 12. The chin support 16 is guided along a path by the pin 124 extending into the slot 130 of the cam member 132.

From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims. 

1. A neck brace for stretching tissue in a neck of a patient, the brace comprising: a torso member positionable on a torso of the patient; a chin support including a chin portion configured for engaging a chin of the patient and a back portion configured for engaging a back of the neck of the patient, the back portion being adjustably connected to the chin portion; an actuation member positioned between the chin support and the torso member and operable to apply a force to the chin support to move the chin support from a first position to a second position, such that the chin of the patient is moved from the first position to the second position, wherein the actuation member is pivotably connected to the torso member and operation of the actuation member simultaneously moves the chin support vertically and laterally.
 2. The neck brace of claim 1 wherein the actuation member includes a guide surface defining a path and a member which is movable along the guide surface while the guide surface is stationary relative to the torso member to move the chin support along a straight section of the path, the guide surface being movable relative to the torso member, the member being movable along the guide surface during movement of the guide surface relative to the torso member to move the chin support along a curved section of the path.
 3. The neck brace of claim 1 wherein the torso member comprises a support member securely positionable on a chest portion of the torso of the patient and wherein the actuation member is pivotably connected to the support member.
 4. The neck brace of claim 3 wherein the support member includes a guide slot enangeable by the actuation member and wherein the guide slot controls a change in an angular relationship between the actuation member and the torso member.
 5. The neck brace of claim 3 wherein the torso member further comprises a vest having front and back portions, the support member connected to the front portion of the vest.
 6. The neck brace of claim 5 wherein the vest includes adjustable straps to secure and position the support member on the chest portion of the patient.
 7. The neck brace of claim 1 wherein the actuation member comprises a drive member operatively associated with interconnecting members, the interconnecting members coupled to the chin support.
 8. The neck brace of claim 7 further comprising a threaded member coupling the drive member and the interconnecting members such that rotation of the threaded member results in movement of the interconnecting member to apply the force to the chin support.
 9. A neck brace for stretching tissue in a neck of a patient, the brace comprising: a chin support configured for engaging a chin of the patient; an actuation member operatively associated with the chin support and operable to apply a force to the chin support to move the chin support from a first position to a second position, the actuation member including a drive member operatively associated with interconnecting members, the interconnecting members coupled to the chin support; and a gear assembly coupling the drive member and the interconnecting members, wherein operation of the actuation member simultaneously moves the chin support vertically and laterally.
 10. An orthosis for stretching tissue around a neck of a patient comprising: a torso member positionable on a torso of the patient; a chin support including a chin portion configured for engaging a chin of the patient and a back portion configured for engaging a back of the neck of the patient, the back portion being adjustable connected to the chin portion; and an actuation member interposed between and operatively associated with the torso member and the chin support and configured to apply a force to the chin support to move the chin support and chin of the patient from a first vertical position to a second vertical position relative to the torso member, thereby stretching the tissue around the neck of the patient, wherein the actuation member is pivotably connected to the torso member such that an angle between the actuation member and the torso member changes as the chin support is moved from the first vertical position to the second vertical position.
 11. The orthosis of claim 10 wherein the torso member comprises a support member securely positionable on a chest portion of the torso of the patient and the actuation member is pivotably connected to the support member such that an angle between the actuation member and the support member changes as the chin support is moved from the first vertical position to the second vertical position.
 12. The orthosis of claim 10 wherein the actuation member comprises a drive member operatively associated with interconnecting members, the interconnecting members coupled to the chin support.
 13. The neck brace of claim 12 further comprising a threaded member coupling the drive member and the interconnecting members such that rotation of the threaded member results in movement of the interconnecting member to apply the force to the chin support.
 14. An orthosis for stretching tissue around a neck of a patient comprising: a torso member positionable on a torso of the patient; a chin support including a chin portion configured for engaging a chin of the patient and a neck portion configured for engaging a back of the neck of the patient; a n actuation member interposed between and operatively associated with the torso member and the chin support and configured to apply a force to the chin support to move the chin support and chin of the patient from a first vertical position to a second vertical position relative to the torso member, thereby stretching the tissue around the neck of the patient, the actuation member including a drive member operatively associated with interconnecting members, the interconnecting members coupled to the chin support; and a gear assembly coupling the drive member and the interconnecting members.
 15. The orthosis of claim 14 wherein the drive member comprises an input member connected to the gear assembly, the input member providing a drive force to rotate the gear assembly.
 16. The orthosis of claim 15 wherein the drive member further comprises a threaded member connected to the interconnecting members and engaging the gear assembly such that rotation of the gear assembly causes rotation of the threaded member, thereby resulting in movement of the interconnecting members to apply the force to the chin support.
 17. An orthosis for stretching tissue around a joint of a patient comprising: a first member positionable on a first body portion of the patient; a second member positionable on a second body portion of the patient, with the joint interposed between the first and second body portions; an actuation mechanism interposed between and operably connected to the first and second members, wherein the actuation mechanism is pivotably connected on to the first member, such that an angular relationship between the actuation mechanism and first member is adjustable; and a support plate interposed between and attached to the first member and the actuation mechanism, wherein the actuation mechanism is pivotably connected to the support plate, the support plate includes a guide slot enagable by the actuation mechanism, and the guide slot controls the change in the angular relationship between the actuation member and the first member. 